Hugh Bonneville and Janet McTeer return as the detective duo who tower above all others – literally – in the new crime two-parter Hunter.

Hugh Bonneville and Janet McTeer have teamed up again, and Bonneville, for one, is delighted. And not just for the usual actorly reasons that they ‘love working together’. In fact, the main reason Bonneville enjoys working with McTeer is her height. ‘Janet is 6’1,’ the 6’2″ actor says. ‘Which is great because I don’t have to bend down all the time.’ High praise indeed.

The pair are reunited in BBC1’s fast-paced new thriller Hunter, in which they star as Detective Superintendent Iain Barclay and his DS Amy Foster. Viewers first met Barclay and Foster in BBC1’s Bafta-nominated drama Five Days, which pulled in 6.7 million viewers when it aired in 2007. Hunter is more than just a sequel, however. It has a new writer, Mick Ford (Ashes to Ashes), and is set over two episodes rather than five. As Bonneville explains: ‘This is like a first cousin of Five Days but it’s not trying to recreate or diminish it. It’s not Five Days Lite. It’s taking a successful format and giving it a new life.’

Bonneville (Notting Hill), 45, reprises his role of the dogged DSI, with McTeer (The Governor), 47, playing that familiar cop drama character: the deputy pulled out of retirement. In Five Days the pair investigated the disappearance of a young mother and her children. In Hunter they’re reunited to lead the hunt for two seven-year-old boys who go missing on the same day. The two incidents appear to be unrelated until photos are emailed to the police of both boys apparently asleep in identical poses, wrapped in white matching blankets. An extremist group is threatening to murder them both unless their demands are met.

Barclay is finding his inexperienced police team increasingly unreliable. In a bid to whip them into shape he summons Foster, his friend and former deputy, who is lazing partially inebriated in the bath when she gets the call. However, McTeer insists that Foster is not an addict: ‘She drinks a lot but she’s not an alcoholic. She smokes; she drinks a lot of coffee. They’re all adrenaline junkies. But she’s a cool customer – very tough.’

This makes her markedly different from McTeer herself, who admits she’s not strong enough to do Foster’s job in real life. ‘I think I’m too soppy,’ she says. ‘I think by definition my emotions are near the surface otherwise I wouldn’t be able to act.’

Bonneville, by contrast, thinks he’d be ‘not bad’ as a detective. ‘But I’m a classic bloke. I can open the fridge and not see the butter when I’m staring right at it,’ he says. ‘Similarly Barclay’s great passion is astronomy; his talent is to see order in the chaos. I look up at the stars and can’t see a pattern but he sees constellations. Foster picks up on things which are blindingly obvious, though sometimes Barclay can’t spot details when they’re under his nose. That’s what makes them a good team.’

The case certainly requires all Barclay and Foster’s skill and intuition. Both face tough ethical decisions about whether to accede to the kidnappers’ demands and thereby risk the hostages’ lives. But unlike slick US crime dramas such as CSI, in which Machiavellian baddies commit crimes with clinical efficiency, the kidnappers in Hunter, like the cops pursuing them, are all too human. They make mistakes of their own and it’s thanks to these that Barclay and his hard-nosed deputy start to work out who’s behind the abductions.

Although McTeer says she has little in common with Foster, she has played a string of similarly tough female roles in dramas such as the ITV1 prison series The Governor and the period film Songcatcher. Her leading role in the US indie film Tumbleweeds, a heart-warming tale of the struggles of a single mother, earned her an Oscar nomination (and won her a Golden Globe) in 2000. Hollywood was banging down McTeer’s door to offer her juicy roles but she decided to return to the UK immediately afterwards. So why did she come back so soon?

‘I think that was a stupid move on my part,’ she admits. ‘The whole movie publicity tour was so gruelling, and at the time my agent was on a break. He would have been, “Come on McTeer! We have to do that, we have to do this!” But I just thought, “I can’t do this. I like it at home.”‘

Thankfully McTeer’s career continued to flourish back in the UK, both on stage and on television. Last year she starred as Mrs Dashwood in the BBC1’s superb adaptation of Sense and Sensibility.

Indeed Jane Austen has given both Hunter’s stars plenty of work. Bonneville, too, has appeared in his fair share of Austen-inspired dramas (Lost in Austen, Miss Austen Regrets, Mansfield Park). The trend hasn’t been intentional, he says, but he thinks you can overdose on a certain type of role. ‘I did actually wear the same pair of trousers in Lost in Austen and Miss Austen Regrets so that was perhaps a bit of overkill,’ he says. ‘Maybe it’s time to hang up the black breeches.’

Bonneville’s major TV role last year was in BBC1’s Bonekickers, a drama about archaeologists solving historical mysteries. It was panned by the critics and lost 37 per cent of its viewers between the first and sixth episodes. Bonneville admits he was surprised by its hostile reception. But, he says, ‘It wasn’t meant to be a serious archaeological investigation. It was an adventure show and people didn’t get that. But if we didn’t hit the right tone for everyone, then mea culpa.’

Thankfully Hunter, with its clever, compelling script and the return of Bonneville and McTeer’s detecting duo, looks likely to win better reviews. Not least from the millions of viewers who were captivated by their superior brand of sleuthing in Five Days.

Hunter is on Sunday and Monday on BBC1 at 9.00pm.